This invention relates to a computer system with an image display device and, more particularly, to a multiwindow display device, which is adapted for use in a computer used as a workstation and forms or opens several windows on a display screen, any one of which can be rendered active as required by an operator.
Recently, it becomes popular to support a "multiwindow manager" in an image display device for use in a workstation. The "multiwindow manager" ensures that a plurality of rectangular image regions (called "windows") on the display screen of the display device, which can overlap one upon another, and that the individual windows function as if each is an independent single image screen. The way the windows are formed or opened on the display screen resembles a plurality of paper documents lying on an office desk, with the document desired for reference on the top. Through an operator's manipulation, it is free to change the window-overlapping order to make any desired window active, change the size of each window or move it around. When a window is selected, its corresponding region on the display screen functions as if it is an independent screen of the display device.
A window on which the operator is working at the moment is generally called "an active window." When a window becomes active, the priority of window display changes and the active window moves on top or in front of the other windows. All the image region of the active window is thus visible, the remaining windows being partially or entirely hidden under the active window.
In conventional manner, in order to select a desired window from among overlapping windows on the display screen and move it to the front, that is, to make the desired window active, a pointing device such as a well-known "mouse" is used. According to an existing operation, the operator watches the screen while rolling the mouse on a flat surface to position a displayed pointing image, a pointer, on a frame line or an icon pattern of the desired window. With an appropriate mouse button pressed, the active window moves on top; this active, frontmost window can be zoomed to nearly fill the display screen. The same procedures should be taken for making another window active.
According to the conventional, manual multiwindow presentation control technique, to make a desired window active, the operator needs to operate a mouse button for each window activation action, thus making the operation troublesome. Particularly, when the operator frequently uses a plurality of windows to perform a task with a workstation, a required manual operation sequence of mouse movement and mouse button operations becomes a critical problem to efficient task execution. This is because the operator's thought has to be interrupted every time the desired window is selected. Consequently, it is unlikely that the operator can utilize the inherent advantages of the multiwindow function.